Buying mixtures of on-paper stamps is one of the least expensive ways to add stamps to your collection. By sorting, soaking and cataloging the stamps yourself, you avoid dealer markup for these services.

Mixtures are also the best place to find recent postally used commemorative stamps, used United States plate number coils and a host of stamps with flaws and varieties that would be difficult to acquire in any other way.

Mixtures are most often sold by weight. The weight includes the paper, carton or cardboard to which the stamps were affixed to do their postal duty. At least half of a 1-pound mixture's weight will consist of useless paper. Foreign sources and some United States dealers use the metric system to weigh their wares. These dealers sell by the kilogram or its fractions, hence the word "kiloware."

Some dealers will do a preliminary sort to weed out obviously damaged stamps. If a mixture is advertised as unsorted, it means that no one has gone through it to pick the better stamps out. It also means that the damaged stamps have not been culled.

Some dealers offer mixtures containing only commemorative stamps or stamps from just one country. Be prepared to pay more for these types of mixtures. The more a mixture is processed before you buy it, the more it will cost you. You are paying for the dealer's time spent preparing it for sale.

The weekly Kitchen Table Philately column in Linn's (page 37 in this issue) is a good place to start. The different reviewers (each named E. Rawolik, "kiloware" spelled backward) offer ideas on where to purchase the best mixtures and the types of stamps you can expect to receive in different types of mixtures. Their columns are detailed reviews of actual units of kiloware available on the market.

Once you receive a mixture of on-paper stamps, what do you do with it? Processing a mixture is time-consuming, but it should also be a lot of fun. Don't be in a rush to soak. Doing some preliminary sorting will save hours of time later and will help to prevent damaging the stamps, Figure 1.

If you purchased a mixture limited to one country, then your first sort has been completed for you. If your mixture contains stamps from many countries you might want to sort them by country, continent or topic depending on how you organize your collection.

When making this first sort, cull the mixture for badly damaged stamps and for those that are affixed to colored paper. The bright red and green envelopes that are used around Christmastime are notorious for bleeding their colors when wet. They will stain and ruin any stamps they come in contact with. Any colored paper, not just green and red, may run and ruin all the stamps it touches, so make sure that you remove and soak all stamps on colored paper separately.

Soak those stamps on colored paper individually using running water or by changing the water after each soak. You may be able to salvage some of them, but don't take the chance of ruining a whole batch of stamps for the sake of the few on colored paper. Use care with colored or heavy cancels as well. Some of the red-ink circular-datestamp cancels used by the United States Postal Service may run and bleed.

Use caution when soaking all stamps that were canceled by handstamps. As a rule of thumb, most machine cancels are stable. Cancels made by handstamps, which often use red or purple ink, may not be. With practice and experience, you will be able to pick out the cancels that will cause problems when soaking.

Sort out stamps that have holographic images as part of their designs. Sometimes these foil-based printed images flake or peel when soaked in water. There are methods, which I will describe in paragraphs that follow, to deal with them.

In the 1990s, the world's postal administrations and mailers embraced self-adhesive postage stamps in a big way. Their convenience and ease of use means that self-adhesives are here to stay. Unfortunately, some are less easily removed from their paper than traditional lick-and-stick stamps.

No thought was given to using a water-soluble adhesive so that the used stamps could be soaked from their paper when Tonga and Sierra Leone issued the first self-adhesive stamps in the 1960s. I have attempted to remove Tongan self-adhesives issued in the 1970s from their paper backings using a variety of solvents, all without success.

Since those early days, adhesive technology has improved. Even so, self-adhesives will not uniformly release in a bath of lukewarm water. It is best to remove self-adhesive stamps from the mixture and soak them separately, but expect that some foreign stamps will not soak off.

Once you finish sorting, you are ready to begin soaking the stamps. I use a 9-inch-by-13-inch rectangular glass baking dish and fill it with about an inch of lukewarm water, Figure 2. I put approximately 50 stamps in the water, face up, and monitor the process carefully from start to finish.

As soon as a stamp floats free from the paper, I remove it from the water, rinse it and place it face down on a thin, old (but clean) bath towel that is reserved just for stamp drying, Figure 3. The stamps will begin to curl as they dry. To counteract the curling, I move the stamps to a drying book just before they are completely dry.

Drying books are commercially available, but you can make your own. They consist of several pages of blotting paper interleaved with sheets of plastic. You place the nearly dry stamps face up on the plastic page, and place the blotting page down on top of the stamps, Figure 4. Keep the drying book flat and place a heavy book on top of it for a day or two. The stamps will then be dry, almost always wrinkle free, and ready to be mounted in your album or placed in a stock-book.

Don't try to rush through this process. If you attempt to help the soaking process along by pulling the stamps from the backing paper before they are ready to release on their own, rips and thins will almost certainly be the result. If you try to soak too many stamps at one time, you will end up with a soggy mess of paper pulp. Don't start soaking unless you have enough time to do the job properly.

As mentioned earlier, self-adhesive stamps should be soaked separately. Most U.S. stamps issued in the past 10 years can be successfully removed from the paper, but they will almost certainly take much longer to float free than lick-and-stick stamps. Use warm (but not hot) water, rather than lukewarm water, for soaking self-adhesive stamps.

For stubborn cases, some collectors resort to a solvent adhesive label remover available in craft stores. These solvents will usually release the stamp, but they may leave a greasy residue and a ruined cancel. In such cases, it may be better to just leave the stamp on the envelope paper.

What should you do with those great-looking hologram stamps? You can try floating them on top of the water in your soaking basin. The objective is to get the backing paper wet but to keep the stamp itself as dry as possible.

You also can attempt using a sweatbox, Figure 5. These, too, are commercially available, but you can make your own. You will need a plastic container with a tight fitting lid and a sponge. Put a half-inch of water in the bottom of the container. Put the sponge in the water and allow it to draw up some of the moisture. Then put the stamp on top of the sponge and put the lid on the container.

It may take several hours or even several days for the stamp to release, but there is much less chance of damaging the hologram or detaching it from the rest of the stamp. When the stamp releases from the paper, move it to the stamp-drying book.

Processing mixtures is relaxing and rewarding, but doing a proper job of it requires time, patience and practice.